* c-common.c (scanf_flag_specs): Add flags ' and I.
	(strftime_flag_pairs): Disallow any pair of the _, - and 0 flags,
	or the ^ and # flags together.
	(scan_char_table): Handle the ' and I flags.
	(format_types): Add ' and I flags for scanf.

testsuite:
	* gcc.dg/c99-scanf-2.c, gcc.dg/format-ext-2.c: Test ' and I
	scanf flags.
	* gcc.dg/format-ext-3.c: Test mutually exclusive pairs of strftime
	flags.

From-SVN: r36842